A typical known interengaging labyrinth seal system is reproduced in detail in a greatly simplified form in FIG. 1. The labyrinth seal 24 which is shown there seals the annular interspace 11 between the (inner) rotating part 12 and the static part 10, which concentrically encompasses it, against throughflow of gas. The interengaging labyrinth seal 24 comprises both stator-side sealing strips 13 which are fastened on the static part 10 and rotor-side sealing strips 14 which are fastened on the rotating part 12, which sealing strips are arranged in a staggered manner and engage radially in the interspaces of the opposite sealing strips in each case.
An interengaging labyrinth seal according to FIG. 1, however, brings a problem along with it:                The large thermally induced displacements of rotor and stator lead to large differences in the clearance of the labyrinth seal system so that the sealing strips migrate from their central position of the installed state and during steady-state conditions do not return, or only partially return, to this position. Since the sealing effect of a labyrinth seal in the resulting displaced position can be negatively affected, the leakage losses become greater and the steady-state power and the efficiency of the machine can be negatively influenced.        
Different configurations of interengaging labyrinth seals, in which the rotor is additionally divided into sections with stepped diameter, are known from U.S. Pat. No. 5,029,876, for example.